Laminate Sheet for Battery Cases Having Thickness Deviation and Pouch-Shaped Battery Case Manufactured Using the Same

ABSTRACT

Disclosed are a laminate sheet for battery cases with improved formability, the laminate sheet for battery cases including, as a preliminary recess portion configured to receive an electrode assembly, a preliminary bottom portion and a preliminary sidewall portion constituting the side surface of the preliminary recess portion, wherein a preliminary sealing portion is located at an outer edge extending from the preliminary sidewall portion, and the thickness of the preliminary sidewall portion is formed so as to be larger than the thickness of the preliminary bottom portion, a pouch-shaped battery case manufactured by forming the laminate sheet, and a battery pack including the pouch-shaped battery case.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a national phase entry under 35 U.S.C. § 371of International Application No. PCT/KR2019/014172 filed Oct. 25, 2019,which claims priority from Korean Patent Application No. 10-2018-0156837filed Dec. 7, 2018, all of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a laminate sheet for battery caseshaving a thickness deviation and a pouch-shaped battery manufacturedusing the same, and more particularly to technology capable of solving aproblem that occurs at the time of forming a recess portion configuredto receive an electrode assembly in a pouch-shaped high-capacitybattery.

BACKGROUND ART

The demand for secondary batteries as energy sources that are capable ofbeing repeatedly charged and discharged for portable electronicproducts, such as mobile phones, tablet PCs, and cleaners has rapidlyincreased, and secondary batteries that are applicable to devices thatrequire high capacity and high efficiency, such as electric vehicles andpower storage apparatuses, have been developed and researched.

Among such secondary batteries is a lithium secondary battery, which hasadvantages, such as high energy density, high voltage, high output, andexcellent lifespan characteristics, and has been widely used for thesereasons.

Secondary batteries are classified into a pouch-shaped secondarybattery, a cylindrical secondary battery, and a prismatic secondarybattery based on the kind of a sheathing material. The pouch-shapedsecondary battery has a structure in which an electrode assembly ismounted in a pouch-shaped case made of a laminate sheet including ametal layer, and has advantages in that the pouch-shaped secondarybattery is easy to manufacture and cost of manufacturing thepouch-shaped secondary battery is low. In addition, it is possible toeasily construct a large-capacity battery pack by connecting a pluralityof pouch-shaped unit cells to each other in series and/or in parallel.

Meanwhile, as the size of the electrode assembly is increased in orderto manufacture a high-capacity pouch-shaped secondary battery, a methodof deeply forming a recess portion configured to receive the electrodeassembly may be used. When considering the durability and thickness ofthe battery case, cracks may be generated due to stretching of the metallayer in the case in which the recess portion is formed to more than apredetermined depth. In addition, a bleaching phenomenon in which apolymer constituting a polymer layer of the battery case is discoloredwhite due to deformation of the polymer may occur.

In order to solve such a problem, a method of increasing the entirethickness of the battery case or increasing the value of R at the timeof forming the recess portion may be used. In the case in which thethickness of the battery case is increased, however, the thickness of abattery cell increases, which becomes an issue when the battery cell isreceived in a battery pack. In the case in which the value of R isincreased, insertability is reduced when the electrode assembly isreceived in the battery case, whereby process efficiency is lowered.

In connection therewith, Patent Document 1 discloses a pouch formingapparatus that indirectly heats corners of an electrode assemblyreceiving portion through a high-frequency induction heater at the timeof pressing the surface of a pouch film in order to form the electrodeassembly receiving portion, thereby improving flexibility of the cornersof the electrode assembly receiving portion.

That is, Patent Document 1 uses a method of heating the corners of theelectrode assembly receiving portion at the time of forming theelectrode assembly receiving portion, but does not suggest a method ofdeeply forming the electrode assembly receiving portion.

Patent Document 2 discloses a pouch film forming apparatus for secondarybatteries including a structure in which a step is formed at the angularpoint of a punch, which is capable of preventing the occurrence of pinholes or cracks at the time of forming a pouch film, but does notsuggest a method of deeply forming a concave recess of the pouch film.

Patent Document 3 discloses a method of manufacturing a battery caseincluding a process of performing deep drawing in the state in which afilm member for forming is attached to a laminate sheet, wherein it ispossible to improve formability of a receiving portion of the laminatesheet.

Therefore, there is a high necessity for development of a pouch-shapedsecondary battery configured to have a structure in which the occurrenceof pin holes or cracks is prevented when a recess configured to receivean electrode assembly is formed deep in order to manufacture ahigh-capacity pouch-shaped battery cell and in which an increase inthickness of a battery case does not affect an increase in thickness ofa battery cell.

Related Art Document

Patent Document 1: Korean Patent Application Publication No.2015-0089556 (2015 Aug. 5)

Patent Document 2: Korean Patent Application Publication No.2014-0131714 (2014 Nov. 14)

Patent Document 3: Korean Patent Application Publication No.2018-0038765 (2018 Apr. 17)

DISCLOSURE Technical Problem

The present invention has been made in view of the above problems, andit is an object of the present invention to provide a laminate sheetconfigured to have a structure in which damage to the laminate sheet isprevented when a recess configured to receive an electrode assembly isformed and in which an increase in thickness of a battery case does notaffect an increase in thickness of a battery cell and a pouch-shapedbattery case manufactured using the same.

Technical Solution

A laminate sheet for battery cases according to an embodiment of thepresent invention provided to accomplish the above object may include,has a preliminary recess portion configured to receive an electrodeassembly, a preliminary bottom portion and a preliminary sidewallportion constituting the side surface of the preliminary recess portion,wherein a preliminary sealing portion may be located at an outer edgeextending from the preliminary sidewall portion, and the thickness ofthe preliminary sidewall portion may be formed so as to be larger thanthe thickness of the preliminary bottom portion.

The laminate sheet may include an outer coating layer, a metal layer,and an inner sealant layer, and at least one of the outer coating layeror the metal layer of the preliminary sidewall portion may be formed soas to be thicker than a corresponding one of the outer coating layer orthe metal layer of the preliminary bottom portion.

The thickness of the metal layer of the preliminary sidewall portion maybe formed so as to be larger than the thickness of the metal layer ofthe preliminary bottom portion.

The thickness of the preliminary sidewall portion may have a thicknessdeviation within a range within which the thickness of the preliminarysidewall portion is larger than the thickness of the preliminary bottomportion.

The laminate sheet may be configured such that the preliminary recessportion configured to receive the electrode assembly and a preliminarycover portion are formed on both sides of a preliminary bending line,and wherein the preliminary cover portion may be formed in a planarshape, and with a thickness equal to the thickness of the preliminarybottom portion.

The laminate sheet may be configured to have a structure in which thepreliminary recess portion configured to receive the electrode assemblyis formed on both sides on the basis of the preliminary bending line ina symmetrical fashion, and the thickness of the preliminary sidewallportion may be formed so as to be larger than the thickness of thepreliminary bottom portion.

The thickness of the preliminary sidewall portion and the thickness ofthe preliminary sealing portion may be formed so as to be larger thanthe thickness of the preliminary bottom portion.

The outer coating layer of the preliminary sidewall portion may be madeof a different material than the outer coating layer of each of thepreliminary bottom portion and the preliminary sealing portion.

The outer coating layer of the preliminary sidewall portion may be madeof a material that exhibits higher elongation than the outer coatinglayer of each of the preliminary bottom portion and the preliminarysealing portion.

In addition, the present invention provides a pouch-shaped battery casemanufactured by forming the laminate sheet for battery cases.

In the pouch-shaped battery case, the thickness of a sidewall portionconstituting the side surface of a recess configured to receive anelectrode assembly may be equal to or larger than the thickness of abottom portion of the recess.

In addition, the present invention provides a pouch-shaped battery cellincluding the pouch-shaped battery case, and also provides a batterypack having pouch-shaped battery cells stacked therein, wherein a bottomportion of one of the battery cells may be disposed so as to face acover portion or a bottom portion of an adjacent battery cell in tightcontact therewith.

DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of a laminate sheet according to a firstembodiment.

FIG. 2 is a sectional view taken along A-A of FIG. 1.

FIG. 3 is a plan view of a laminate sheet according to a secondembodiment.

FIG. 4 is a sectional view taken along A′-A′ of FIG. 3.

FIG. 5 is a partial sectional view showing the thickness of a laminatesheet according to a third embodiment.

FIG. 6 is a reference view in which a process of manufacturing thelaminate sheet according to the third embodiment is reflected.

FIG. 7 is a partial sectional view showing the thickness of a laminatesheet according to a fourth embodiment.

FIG. 8 is a partial sectional view showing the thickness of a laminatesheet according to a fifth embodiment.

FIG. 9(a) is a sectional view of a lower case of a pouch-shaped batterymanufactured using a laminate sheet according to the present invention,and FIG. 9(b) is a sectional view of a lower case of a pouch-shapedbattery manufactured using a conventional laminate sheet.

BEST MODE

Now, preferred embodiments of the present invention will be described indetail with reference to the accompanying drawings such that thepreferred embodiments of the present invention can be easily implementedby a person having ordinary skill in the art to which the presentinvention pertains. In describing the principle of operation of thepreferred embodiments of the present invention in detail, however, adetailed description of known functions and configurations incorporatedherein will be omitted when the same may obscure the subject matter ofthe present invention.

In addition, the same reference numbers will be used throughout thedrawings to refer to parts that perform similar functions or operations.In the case in which one part is said to be connected to another part inthe specification, not only may the one part be directly connected tothe other part, but also, the one part may be indirectly connected tothe other part via a further part. In addition, that a certain elementis included does not mean that other elements are excluded, but meansthat such elements may be further included unless mentioned otherwise.

A laminate sheet for battery cases according to the present inventionincludes an outer coating layer, a metal layer, and an inner sealantlayer.

It is required for the outer coating layer not to be affected byexternal environmental change and not to be bleached since the outercoating layer is stretched during a process of forming a battery case,and therefore excellent tensile strength and weather resistance arenecessary. For example, a polyester-based resin, such as polyethylenenaphthalate (PEN), polyethylene terephthalate (PET), or polybutyleneterephthalate (PBT), a polyolefin-based resin, such as polyethylene (PE)or polypropylene (PP), a polystyrene-based resin, such as polystyrene, apolyvinyl chloride-based resin, or a polyvinylidene chloride-based resinmay be used as a polymer resin constituting the outer coating layer.

The metal layer may be made of aluminum (Al), an aluminum alloy, orstainless steel in order to exhibit a function of improving strength ofthe battery case in addition to a function of preventing introduction offoreign matter, such as gas and moisture, or leakage of an electrolyticsolution.

A single material or a combination of two or more materials may be usedas the metal layer. In the case in which the metal layer is made of acombination of two or more materials, the metal layer may be configuredto have a multilayered structure, or may be configured such thatdifferent materials are partially applied.

Stainless steel is a material that exhibits higher strength thanaluminum. In the case in which stainless steel is used as the metallayer, therefore, it is possible to improve formability of the batterycase. Consequently, it is possible to prevent pin holes or cracks frombeing generated during formation of an electrode assembly receivingrecess and to form the battery case such that the depth of an electrodeassembly receiving portion is relatively large, compared to a batterycase including an aluminum layer.

Also, in the case in which stainless steel is used as the metal layer ofthe battery case, it is possible to form a metal layer having a smallerthickness than aluminum. Consequently, the thickness of the battery casemay be reduced, whereby it is possible to manufacture a secondarybattery having an increased ratio of capacity to volume.

A polymer resin that exhibits thermal fusibility (thermal adhesiveness)and has low hygroscopicity to the electrolytic solution in order toinhibit permeation of the electrolytic solution may be used as the innerresin layer. For example, the inner resin layer may be made of castpolypropylene (CPP).

The laminate sheet includes, as a preliminary recess portion configuredto receive the electrode assembly, a preliminary bottom portion and apreliminary sidewall portion constituting the side surface of thepreliminary recess portion, and a preliminary sealing portion is locatedat an outer edge extending from the preliminary sidewall portion.

In a concrete example, the laminate sheet may be configured such that apreliminary recess portion configured to receive the electrode assemblyand a preliminary cover portion are formed at both sides on the basis ofa preliminary bending line, the preliminary cover portion is formed in aplanar shape, and the preliminary cover portion has a thickness equal tothe thickness of the preliminary bottom portion.

In connection therewith, FIG. 1 is a plan view of a laminate sheetaccording to a first embodiment, and FIG. 2 is a sectional view takenalong A-A of FIG. 1.

Referring to FIGS. 1 and 2, the laminate sheet 100 is generally used inthe state of being wound in the form of a roll, and a portion of thelaminate sheet withdrawn in order to form an electrode assemblyreceiving recess is shown.

A preliminary bending line 105 is formed along the central part of thelaminate sheet 100 in the winding direction of the laminate sheet, and apreliminary cover portion 104 and a preliminary recess portion 110 arelocated on the basis of the preliminary bending line 105. The laminatesheet, which is formed as a battery case, is bent along the preliminarybending line 105 and is then sealed, whereby a battery cell iscompleted. The battery case may include a lower case having a recessportion configured to receive an electrode assembly formed therein andan upper case having a cover portion coupled to the upper part of therecess portion.

The preliminary recess portion 110 includes a preliminary bottom portion101 and a preliminary sidewall portion 102, and a preliminary sealingportion 103 is located at an outer edge extending from the preliminarysidewall portion 102.

The laminate sheet 100 includes an outer coating layer 100 a, a metallayer 100 b, and an inner sealant layer 100 c. The thicknesses of theouter coating layer 100 a, the metal layer 100 b, and the inner sealantlayer 100 c of the preliminary bottom portion 101 are equal to thethicknesses of the outer coating layer 100 a, the metal layer 100 b, andthe inner sealant layer 100 c of the preliminary cover portion 104,respectively, and the thicknesses of the outer coating layer 100 a, themetal layer 100 b, and the inner sealant layer 100 c of the preliminarysidewall portion 102 are equal to the thicknesses of the outer coatinglayer 100 a, the metal layer 100 b, and the inner sealant layer 100 c ofthe preliminary sealing portion 103, respectively.

However, the thicknesses of the preliminary sidewall portion 102 and thepreliminary sealing portion 103 are formed so as to be larger than thethicknesses of the preliminary bottom portion 101 and the preliminarycover portion 104. Specifically, the thicknesses of the metal layers 100b of the preliminary sidewall portion 102 and the preliminary sealingportion 103 are larger than the thicknesses of the metal layers 100 b ofthe preliminary bottom portion 101 and the preliminary cover portion104.

For example, the thicknesses of the metal layers 100 b of thepreliminary sidewall portion 102 and the preliminary sealing portion 103may be formed so as to be 120% to 300% of the thicknesses of the metallayers 100 b of the preliminary bottom portion 101 and the preliminarycover portion 104.

In the case in which the numerical range is less than 120%, thethicknesses of a sidewall portion and a sealing portion of an electrodeassembly receiving portion may be smaller than the thicknesses of abottom portion and a cover portion of the electrode assembly receivingportion after formation of the battery case, which is undesirable. Inthe case in which the numerical range is greater than 300%, the weightand volume of the battery case are increased, whereby energy density isreduced, which is also undesirable.

In addition, the thicknesses of the outer coating layers 100 a and theinner sealant layers 100 c of the preliminary sidewall portion 102 andthe preliminary sealing portion 103 are formed so as to be equal to thethicknesses of the outer coating layers 100 a and the inner sealantlayers 100 c of the preliminary bottom portion 101 and the preliminarycover portion 104.

Alternatively, unlike what is shown in FIG. 2, at least one of the outercoating layer and the metal layer of the preliminary sidewall portionmay be formed so as to be thicker than a corresponding one of the outercoating layer and the metal layer of the preliminary bottom portion. Thethicknesses of the outer coating layers 100 a and the metal layers 100 bof the preliminary sidewall portion 102 and the preliminary sealingportion 103 may be formed so as to be larger than the thicknesses of theouter coating layer 100 a and the metal layer 100 b of the preliminarybottom portion 101. For example, the sum of the thicknesses of the outercoating layers 100 a and the metal layers 100 b of the preliminarysidewall portion 102 and the preliminary sealing portion 103 may beformed so as to be 120% to 300% of the sum of thicknesses of the outercoating layer 100 a and the metal layer 100 b of the preliminary bottomportion 101.

In a concrete example, the laminate sheet may be configured to have astructure in which preliminary recess portions configured to receive theelectrode assembly are formed at both sides on the basis of thepreliminary bending line in a symmetrical fashion and in which thethickness of the preliminary sidewall portion is formed so as to belarger than the thickness of the preliminary bottom portion.

In connection therewith, FIG. 3 is a plan view of a laminate sheetaccording to a second embodiment, wherein a portion of the laminatesheet withdrawn in order to form an electrode assembly receiving recessis shown as in FIG. 1, and FIG. 4 is a sectional view taken along A′-A′of FIG. 3.

Referring to FIGS. 3 and 4, a preliminary bending line 205 is formedalong the central part of the laminate sheet 200 in the windingdirection of the laminate sheet 200, and preliminary recess portions 210configured to receive an electrode assembly are located on the basis ofthe preliminary bending line 205. The laminate sheet, which is formed asa battery case, is bent along the preliminary bending line 205 and isthen sealed, whereby a battery cell is completed. The battery case mayinclude a lower case having a recess portion configured to receive theelectrode assembly formed therein and an upper case having a coverportion coupled to the upper part of the recess portion, the upper casehaving a recess portion configured to receive the electrode assemblyformed therein.

The preliminary recess portion 210 include a preliminary bottom portion201 and a preliminary sidewall portion 202, and a preliminary sealingportion 203 is located at an outer edge extending from the preliminarysidewall portion 202.

The laminate sheet 200 includes an outer coating layer 200 a, a metallayer 200 b, and an inner sealant layer 200 c. The thicknesses of theouter coating layer 200 a, the metal layer 200 b, and the inner sealantlayer 200 c of the preliminary sidewall portion 202 are equal to thethicknesses of the outer coating layer 200 a, the metal layer 200 b, andthe inner sealant layer 200 c of the preliminary sealing portion 203,respectively, and the thicknesses of the outer coating layer 200 a, themetal layer 200 b, and the inner sealant layer 200 c of the preliminarysidewall portion 202 are equal to the thicknesses of the outer coatinglayer 200 a, the metal layer 200 b, and the inner sealant layer 200 c ofthe preliminary sealing portion 203, respectively.

However, the thicknesses of the preliminary sidewall portion 202 and thepreliminary sealing portion 203 are formed so as to be larger than thethickness of the preliminary bottom portion 201. Specifically, thethicknesses of the metal layers 200 b of the preliminary sidewallportion 202 and the preliminary sealing portion 203 are larger than thethickness of the metal layer 200 b of the preliminary bottom portion201.

For example, the thicknesses of the metal layers 200 b of thepreliminary sidewall portion 202 and the preliminary sealing portion 203may be formed so as to be 120% to 300% of the thickness of the metallayer 200 b of the preliminary bottom portion 201.

In the case in which the numerical range is less than 120%, thethicknesses of a sidewall portion and a sealing portion of an electrodeassembly receiving portion may be smaller than the thicknesses of abottom portion of the electrode assembly receiving portion afterformation of the battery case, which is undesirable. In the case inwhich the numerical range is greater than 300%, the weight and volume ofthe battery case are increased, whereby energy density is reduced, whichis also undesirable.

In addition, the thicknesses of the outer coating layers 200 a and theinner sealant layers 200 c of the preliminary sidewall portion 202 andthe preliminary sealing portion 203 are formed so as to be equal to thethicknesses of the outer coating layer 200 a and the inner sealant layer200 c of the preliminary bottom portion 201.

Alternatively, unlike what is shown in FIG. 4, at least one of the outercoating layer and the metal layer of the preliminary sidewall portionmay be formed so as to be thicker than a corresponding one of the outercoating layer and the metal layer of the preliminary bottom portion. Thethicknesses of the outer coating layers 200 a and the metal layers 200 bof the preliminary sidewall portion 202 and the preliminary sealingportion 203 may be formed so as to be larger than the thicknesses of theouter coating layer 200 a and the metal layer 200 b of the preliminarybottom portion 201.

For example, the sum of the thicknesses of the outer coating layers 200a and the metal layers 200 b of the preliminary sidewall portion 202 andthe preliminary sealing portion 203 may be formed so as to be 120% to300% of the sum of thicknesses of the outer coating layer 200 a and themetal layer 200 b of the preliminary bottom portion 201.

Meanwhile, as a modification of the laminate sheet 100 of FIGS. 1 and 2,the laminate sheet may be configured such that the preliminary bottomportion, the preliminary sealing portion, and the preliminary coverportion have the same thickness and such that only the preliminarysidewall portion has a relatively large thickness, and as a modificationof the laminate sheet 200 of FIGS. 3 and 4, the preliminary bottomportion and the preliminary sealing portion may have the same thicknesswhile only the preliminary sidewall portion has a relatively largethickness.

In connection therewith, FIG. 5 is a partial sectional view showing thethickness of a laminate sheet according to a third embodiment.

Referring to FIG. 5, the laminate sheet includes an outer coating layer111, a metal layer 112, and an inner sealant layer 113, and the totalthickness of a preliminary bottom portion 117 is equal to totalthickness of a preliminary sealing portion 119. Specifically, thethicknesses of the outer coating layer 111, the metal layer 112, and theinner sealant layer 113 of the preliminary bottom portion 117 are equalto the thicknesses of the outer coating layer 111, the metal layer 112,and the inner sealant layer 113 of the preliminary sealing portion 119,respectively.

The thickness of a preliminary sidewall portion 118 is formed so as tobe larger than the thicknesses of the preliminary bottom portion 117 andthe preliminary sealing portion 119, wherein the thickness b1 of themetal layer 112 of the preliminary sidewall portion 118 is formed so asto be larger than the thickness b1′ of the metal layer 112 of each ofthe preliminary bottom portion 117 and the preliminary sealing portion119. However, the thickness a1 of the outer coating layer 111 and thethickness c1 of the inner sealant layer 113 of the preliminary sidewallportion 118 are equal to the thickness a1′ of the outer coating layer111 and the thickness c1′ of the inner sealant layer 113 of each of thepreliminary bottom portion 117 and the preliminary sealing portion 119,respectively.

Meanwhile, in order to manufacture the laminate sheet having thestructure shown in FIG. 5, the inner sealant layer, the metal layer, andthe outer coating layer may be sequentially stacked in a plane, and maythen be laminated.

In connection therewith, FIG. 6 is a reference view in which a processof manufacturing the laminate sheet according to the third embodiment isreflected. In this case, each of an outer coating layer 111′ and a metallayer 112′, excluding an inner sealant layer 113′, has the same form asthat of FIG. 5. However, the inner sealant layer 113′ of a preliminarysidewall portion 118′ may be formed so as to be thinner than the metallayer 112′ of the preliminary sidewall portion, which has a thick form.

In the case in which the laminate sheet configured such that the metallayer of the preliminary sidewall portion is relatively thick is used,as described above, it is possible to prevent damage to the laminatesheet even in the case in which the electrode assembly receiving recessis formed deep.

In a concrete example, the thickness of the preliminary sidewall portionmay have thickness deviation within a range within which the thicknessof the preliminary sidewall portion is larger than the thickness of thepreliminary bottom portion.

In connection therewith, FIG. 7 is a partial sectional view showing thethickness of a laminate sheet according to a fourth embodiment.

Referring to FIG. 7, the laminate sheet includes an outer coating layer121, a metal layer 122, and an inner sealant layer 123, and the totalthickness of a preliminary bottom portion 127 is equal to totalthickness of a preliminary sealing portion 129. Specifically, thethicknesses of the outer coating layer 121, the metal layer 122, and theinner sealant layer 123 of the preliminary bottom portion 127 are equalto the thicknesses of the outer coating layer 121, the metal layer 122,and the inner sealant layer 123 of the preliminary sealing portion 129,respectively.

The thickness of a preliminary sidewall portion 128 is formed so as tobe larger than the thicknesses of the preliminary bottom portion 127 andthe preliminary sealing portion 129, wherein the thickness b2 of themetal layer 122 of the preliminary sidewall portion 128 may havethickness deviation within a range within which the thickness b2 of themetal layer 122 of the preliminary sidewall portion 128 is larger thanthe thickness b2′ of the metal layer 112 of each of the preliminarybottom portion 127 and the preliminary sealing portion 129.

That is, the metal layer 122 of the preliminary sidewall portion 128 maybe configured to have a structure in which the thickness of the metallayer gradually increases toward the preliminary bottom portion 127.

However, the thickness a2 of the outer coating layer 121 and thethickness c2 of the inner sealant layer 123 of the preliminary sidewallportion 128 are equal to the thickness a2′ of the outer coating layer121 and the thickness c2′ of the inner sealant layer 123 of each of thepreliminary bottom portion 127 and the preliminary sealing portion 129,respectively.

In the case in which the laminate sheet configured to have a structurein which the thickness of the metal layer gradually increases toward thepreliminary bottom portion is used, as described above, it is possibleto prevent damage to the laminate sheet even in the case in which theelectrode assembly receiving recess is formed deep. As a result, it ispossible to obtain the effects of improving yield and increasing energydensity.

Alternatively, unlike the structure of FIG. 7, the metal layer of thepreliminary sidewall portion may be configured to have a structure inwhich the thickness of the metal layer gradually decreases toward thepreliminary bottom portion, or may be configured to have a structure inwhich the central part of the preliminary sidewall portion is thethickest and the thickness of the preliminary sidewall portion graduallydecreases toward the preliminary sealing portion and the preliminarybottom portion.

FIG. 8 is a partial sectional view showing the thickness of a laminatesheet according to a fifth embodiment.

Referring to FIG. 8, the laminate sheet includes an outer coating layer311, a metal layer 312, and an inner sealant layer 313, and the totalthickness of a preliminary bottom portion 317 is equal to totalthickness of a preliminary sealing portion 319. Specifically, thethicknesses of the outer coating layer 311, the metal layer 312, and theinner sealant layer 313 of the preliminary bottom portion 317 are equalto the thicknesses of the outer coating layer 311, the metal layer 312,and the inner sealant layer 313 of the preliminary sealing portion 319,respectively.

The thickness of a preliminary sidewall portion 318 is formed so as tobe larger than the thicknesses of the preliminary bottom portion 317 andthe preliminary sealing portion 319, wherein the thickness a3 of theouter coating layer 311 and the thickness b3 of the metal layer 312 ofthe preliminary sidewall portion 318 are formed so as to be larger thanthe thickness a3′ of the outer coating layer 311 and the thickness b3′of the metal layer 312 of each of the preliminary bottom portion 317 andthe preliminary sealing portion 319, respectively. Optionally, thethickness c3 of the inner sealant layer 313 of the preliminary sidewallportion 318 may be formed so as to be equal to or greater than thethickness c3′ of the inner sealant layer 313 of the preliminary bottomportion 317 and the preliminary sealing portion 319.

In the case in which the laminate sheet configured to have a structurein which the outer coating layer and the metal layer of the preliminarysidewall portion are relatively thick is used, as described above, it ispossible to prevent the occurrence of a bleaching phenomenon at the timeof forming the electrode assembly receiving recess due to an increase inthickness of the outer coating layer and to form a deep electrodeassembly receiving recess due to an increase in thickness of the metallayer.

Here, the outer coating layer constituting the preliminary sidewallportion may be made of a different material than the outer coating layerof each of the preliminary bottom portion and the preliminary sealingportion. Specifically, the outer coating layer constituting thepreliminary sidewall portion may be made of a material that exhibitshigher elongation than the outer coating layer of each of thepreliminary bottom portion and the preliminary sealing portion. In thiscase, the present invention has an advantage in that it is possible tomore securely prevent the occurrence of a bleaching phenomenon which mayoccur as the outer coating layer is stretched at the time of pressing toform the recess portion so as to have a large depth.

In connection therewith, for example, a fluoro-resin-based materialincluding a fluorinated resin copolymer may be used as the outer coatinglayer constituting the preliminary sidewall portion, and apolyester-based or polyethylene-based material, which is generally used,may be used as the outer coating layer of each of the preliminary bottomportion and the preliminary sealing portion.

The present invention provides a pouch-shaped battery case manufacturedby forming a laminate sheet for battery cases as described above.Specifically, since a laminate sheet configured such that the thicknessof a preliminary sidewall portion is relatively thick is pressed tomanufacture a battery case, even in the case in which the preliminarysidewall portion is stretched as the result of forming an electrodeassembly receiving recess and thus the thickness of the preliminarysidewall portion is reduced, the thickness of a sidewall portionconstituting the side surface of the recess may be equal to or largerthan the thickness of a bottom portion of the recess, compared to abattery case manufactured using a conventional laminate sheet.

In connection therewith, FIG. 9(a) is a sectional view of a lower caseof a pouch-shaped battery manufactured using a laminate sheet accordingto the present invention, and FIG. 9(b) is a sectional view of a lowercase of a pouch-shaped battery manufactured using a conventionallaminate sheet.

Referring to FIG. 9(a), a pouch-shaped battery case 400 is a batterycase manufactured using a laminate sheet according to the presentinvention, wherein a recess configured to receive an electrode assemblyis formed in the pouch-shaped battery case, the recess includes a bottomportion 401 and a sidewall portion 402, and a sealing portion 403extends outwards from the sidewall portion 402.

The pouch-shaped battery case 400 may be configured such that thethickness B1 of the bottom portion 401, the thickness B2 of the sidewallportion 402, and the thickness B3 of the sealing portion 403 are equalto each other, or may be configured such that the thickness B2 of thesidewall portion 402 is larger than the thickness B1 of the bottomportion 401 and the thickness B3 of the sealing portion 403.

In contrast, referring to FIG. 9(b), it can be seen that a pouch-shapedbattery case 410 manufactured using a conventional laminate sheet, suchas a laminate sheet having a uniform thickness, has a structure in whichthe thickness B1′ of a bottom portion 411 is equal to the thickness B3′of a sealing portion 413 while the thickness B2′ of a sidewall portion412 is relatively small. The reason for this is that the sidewallportion 412 becomes thin as the result of being stretched duringformation of a recess.

That is, in the pouch-shaped battery case according to the presentinvention, the thickness of the sidewall portion of the recess ismaintained so as to be equal to or larger than the thickness of thebottom portion of the recess even in the case in which the recessconfigured to receive the electrode assembly is formed, whereby it ispossible to prevent the occurrence of a problem in that cracks areformed due to the small thickness of the laminate sheet and it ispossible to form the recess deeper than a conventional pouch-shapedsecondary battery.

Meanwhile, the pouch-shaped battery case according to the presentinvention includes the bottom portion, the sidewall portion, and thesealing portion, wherein each of a portion of the bottom portionconnected to the lower part 422 of the sidewall portion and a portion ofthe sealing portion connected to the upper part 421 of the sidewallportion may have a thickness equal to the thickness of the sidewallportion or may have a thickness larger than the thickness of the centralpart of the bottom portion and the thickness of the outer end of thesealing portion.

In addition, the present invention provides a battery pack havingpouch-shaped battery cells, each of which includes the pouch-shapedbattery case, stacked therein, wherein a bottom portion of one of thebattery cells is disposed so as to face a cover portion or a bottomportion of another battery cell neighboring thereto in tight contacttherewith.

In general, the pouch-shaped battery cells are received in the batterypack in the state of being stacked such that recess portions ofneighboring battery cells face each other. For pouch-shaped batterycells manufactured using the laminate sheet of FIGS. 1 and 2, the bottomportion of one of the battery cells may be disposed so as to face thecover portion of another battery cell neighboring thereto in tightcontact therewith. For pouch-shaped battery cells manufactured using thelaminate sheet of FIGS. 3 and 4, the bottom portion of one of thebattery cells may be disposed so as to face the bottom portion ofanother battery cell neighboring thereto in tight contact therewith.

A person having ordinary skill in the art to which the present inventionpertains will appreciate that various applications and modifications arepossible based on the above description without departing from the scopeof the present invention.

DESCRIPTION OF REFERENCE SYMBOLS

100, 200: Laminate sheets

110, 120: Preliminary recess portions

101, 117, 127, 201, 317: Preliminary bottom portion

102, 118, 118′, 128, 202, 318: Preliminary sidewall portions

103, 119, 129, 203, 319: Preliminary sealing portions

104: Preliminary cover portion

105, 205: Preliminary bending lines

100 a, 200 a, 111, 111′, 121, 311: Outer coating layers

100 b, 200 b, 112, 112′, 122, 312: Metal layers

100 c, 200 c, 113, 113′, 123, 313: Inner sealant layers

400, 410: Pouch-shaped battery cases

401, 411: Bottom portions

402, 412: Sidewall portions

403, 413: Sealing portions

421: Upper part of sidewall portion

422: Lower part of sidewall portion

a1, a2, a1′, a2′, a3, a3′: Thicknesses of outer coating layers

b1, b2, b1′, b2′, b3, b3′: Thicknesses of metal layers

c1, c2, c1′, c2′, c3, c3′: Thicknesses of inner sealant layers

B1, B1′: Thicknesses of bottom portions

B2, B2′: Thicknesses of sidewall portions

B3, B3′: Thicknesses of sealing portions

INDUSTRIAL APPLICABILITY

As is apparent from the above description, in a laminate sheet forbattery cases according to the present invention, it is possible toprevent pin holes or cracks from being generated at the time of formingan electrode assembly receiving recess.

In addition, the electrode assembly receiving recess may be formed deep,whereby it is possible to receive a thick electrode assembly, andtherefore it is possible to manufacture a high-capacity battery cell.

In addition, since a laminate sheet for battery cases configured suchthat only a preliminary side portion of the electrode assembly receivingrecess is thick is used, whereby it is possible to prevent theoccurrence of a problem in that the thickness of a battery cell isincreased in the case in which a battery case is manufactured using alaminate sheet that is generally thick.

1. A laminate sheet for battery cases, comprising: a preliminary recessportion configured to receive an electrode assembly, a preliminarybottom portion and a preliminary sidewall portion constituting a sidesurface of the preliminary recess portion, and a preliminary sealingportion located at an outer edge extending from the preliminary sidewallportion, wherein a thickness of the preliminary sidewall portion islarger than a thickness of the preliminary bottom portion.
 2. Thelaminate sheet for battery cases according to claim 1, wherein thelaminate sheet for battery cases comprises an outer coating layer, ametal layer, and an inner sealant layer, and at least one of an outercoating layer or a metal layer of the preliminary sidewall portion isthicker than a corresponding one of an outer coating layer or a metallayer of the preliminary bottom portion.
 3. The laminate sheet forbattery cases according to claim 1, wherein a thickness of a metal layerof the preliminary sidewall portion is larger than a thickness of ametal layer of the preliminary bottom portion.
 4. The laminate sheet forbattery cases according to claim 1, wherein the thickness of thepreliminary sidewall portion has a thickness deviation within a rangewithin which the thickness of the preliminary sidewall portion is largerthan the thickness of the preliminary bottom portion.
 5. The laminatesheet for battery cases according to claim 1, wherein the laminate sheetis configured such that the preliminary recess portion configured toreceive the electrode assembly and a preliminary cover portion areformed on both sides of a preliminary bending line, and wherein thepreliminary cover portion is formed in a planar shape and with athickness equal to the thickness of the preliminary bottom portion. 6.The laminate sheet for battery cases according to claim 1, wherein thelaminate sheet is configured to have a structure in which thepreliminary recess portion configured to receive the electrode assemblyis formed on both sides of a preliminary bending line in a symmetricalfashion, and the thickness of the preliminary sidewall portion is largerthan the thickness of the preliminary bottom portion.
 7. The laminatesheet for battery cases according to claim 1, wherein the thickness ofthe preliminary sidewall portion and a thickness of the preliminarysealing portion is larger than the thickness of the preliminary bottomportion.
 8. The laminate sheet for battery cases according to claim 2,wherein the outer coating layer of the preliminary sidewall portion ismade of a different material than the outer coating layer of each of thepreliminary bottom portion and the preliminary sealing portion.
 9. Thelaminate sheet for battery cases according to claim 8, wherein the outercoating layer of the preliminary sidewall portion is made of a materialthat exhibits higher elongation than the outer coating layer of each ofthe preliminary bottom portion and the preliminary sealing portion. 10.A pouch-shaped battery case manufactured by forming the laminate sheetaccording to claim
 7. 11. The pouch-shaped battery case according toclaim 10, wherein a thickness of a sidewall portion constituting a sidesurface of a recess configured to receive an electrode assembly is equalto or larger than a thickness of a bottom portion of the recess.
 12. Apouch-shaped battery cell comprising the pouch-shaped battery caseaccording to claim
 10. 13. A battery pack having pouch-shaped batterycells according to claim 12 stacked therein, wherein a bottom portion ofone of the battery cells is disposed so as to face a cover portion or abottom portion of an adjacent battery cell in tight contact therewith.14. The laminate sheet for battery cases according to claim 1, whereinthe entire preliminary sidewall portion has a thickness that is largerthan a thickest part of the preliminary bottom portion.